The seasonally adjusted annual rate (SAAR) of new vehicle sales is expected to fall short of the average analyst estimate calculated by Thomson Reuters of 15.25 million. General Motors Co said the sales rate would be around 15 million vehicles, while Morgan Stanley predicted 15.1 million.

"This is slightly lower than the pace the industry has been running since last October, but it still marks the sixth consecutive month of at least 15 million units," said Kurt McNeil, GM’s head of U.S. sales operations.

"Here’s what’s important: Nearly every economic pillar of light vehicle sales is strong enough to keep the SAAR in the 15 million to 15.5 million unit range for the entire year," McNeil added during a conference with analysts and reporters.

Overall, industry new car sales for April are expected to rise 10.4 percent from a year ago, according to Edmunds.com.

Such a rise would indicate a continuation of the moderate recovery for the industry since its plunge in 2009 to the lowest sales since World War Two, adjusted for population.

Monthly auto sales are an early sign of consumer spending. For all of 2012, U.S. auto sales rose 13 percent to 14.5 million light vehicles. That was still below the 16.7 million vehicles the U.S. auto industry sold on average in the 10 years ending in 2007.

GM said lower sales by some of its rivals to rental car agencies, governments and companies, or "fleet" business, accounted for some of the shortfall in the sales rate in April.

But analysts noted there was higher demand from customers in April compared with the same period last year, indicating that the sales gains were more profitable.

Morgan Stanley analyst Adam Jonas said the "retail" annual sales rate was around 12.5 million vehicles, well above the roughly 11.5 million rate from last year.

"I don’t think we need to ring any alarm bells," said TrueCar.com analyst Jesse Toprak. "It’s still a very healthy marketplace that is recovering on merit, meaning that consumer demand is propelling the market."

Pickup trucks and SUVs are traditionally the strongest aspects of the domestic automakers’ lineups, even as all three have diversified to include more smaller cars since record-high gasoline prices in 2008 and the industry downturn in 2009.

GM, Ford and Chrysler Group LLC posted better-than-expected sales for the month. Executives said the boom in pickup trucks is under way as housing construction and home prices march higher. Sales of pickup trucks, which are much favored by contractors and tradesmen, have historically been tied to the housing construction market.

"The full-size pickup truck segment continues to show signs of strength, supported by replacement demand and the recovery in
housing," said Erich Merkle, Ford U.S. sales analyst.

Truck sales have grown at three times the rate of the U.S. auto industry this year, Merkle said. Ford said the small utility segment, which includes the Ford Escape crossover, accounted for 15 percent of the industry last month, 1 percentage point higher than a year ago.

Toyota, the third-largest automaker in the U.S. market, showed a drop of 1.1 percent in April sales, missing analysts’ expectations. Honda Motor Co Ltd, the No. 5 automaker by sales in the U.S. market, showed a gain of 7 percent, in line with estimates.

First-quarter U.S. housing starts rose 36 percent, while home prices rose 9.3 percent in February, said Jenny Lin, Ford economist. Pickup truck sales are strongest when the construction industry is on the rise.

GM’s primary pickup truck, the Silverado, had an April sales rise of 28 percent. Chrysler’s Ram pickups rose 49 percent. Ford’s F-Series pickup trucks, the best-selling models in the U.S. market for 36 years, showed a 24 percent increase.

Automakers that are more reliant on passenger cars saw a less robust performance during the month. Volkswagen AG reported a sales decline of 10 percent. Nissan Motor Co’s April sales rose 23 percent but slightly missed analysts’ expectations. Nissan announced it is cutting prices on seven models that represent 65 percent of its U.S. offerings.

Jonathan Browning, president and chief executive of Volkswagen Group of America, said industrywide sales of midsize sedans rose only 2.7 percent in the first quarter. Ford said industry sales of full-size pickup trucks were up 20 percent.